The integrated services digital network (ISDN) and its associated message oriented signaling protocols place new and demanding requirements on core switching technologies. In order to meet the ISDN specification, an efficient method of interconnecting a large number of high performance processors in a distributed processing system must be provided.
Previously developed systems suffered from a variety of inadequacies. First, the number of simultaneous connections between processing elements is limited, and the rate at which connections may be achieved is unsuitable, particularly for future applications. Preferably, up to thirty-two simultaneous connections would be supported, with a maximum connection rate approaching 2.5 million connections per second.
Further, present day systems do not offer flexibility in optimizing the cost of the system versus the failsafe mechanisms for overcoming partial system failures. Because the amount of system redundancy will vary depending on the application in which the switching network is used, it is beneficial that the switching network allow for selective redundancy for providing high availability in the most important subsystems.
Additionally, present day switching networks do not allow for cost effective growth capabilities, but rather, force the user to buy a new switching network to accommodate system expansion. Thus, present day switching networks do not offer both short and long term cost effectiveness for growing companies.
Another important aspect of switching networks is their ability to isolate and detect faults. In the telecommunications area, it is important to detect and isolate errors so that faulty data does not propagate through to other processing systems.
Thus, a need has arisen for a switching network capable of a large number of simultaneous connections and a fast connection rate, which offers high system availability and growth possibilities. Furthermore, the switching network system should have an effective means for detecting and isolating system faults and taking corrective measures.